Step 1

Buns: Brush the insert of a 5-to-6-quart slow cooker with butter. Line bottom with parchment; brush parchment with butter. Combine warm water, yeast, and honey in a bowl; let stand until foamy, about 5 minutes. Add flour and salt.

Step 2

Beat on low speed until just combined. Increase speed to medium and beat 5 minutes. Let stand 10 minutes. Meanwhile, combine butter, both sugars, and cinnamon in a bowl; mix until smooth.

Step 3

Preheat slow cooker. Turn dough out onto a lightly floured work surface and roll into a rectangle, about 9 by 15 inches. Sprinkle dough evenly with cinnamon-sugar mixture. Starting from one long side, roll into a log, pinching seams to seal in filling. Slice log into 10 to 12 rounds, each about 1 1/2 inches thick.

Step 4

Arrange rolls, cut-sides down, in cooker. Wrap lid tightly with a clean kitchen towel, gathering ends at top (to absorb condensation). Cover and cook on high until cooked through, 1 1/2 hours. After 1 hour, rotate cooker insert 180 degrees to prevent scorching. Turn out onto a wire rack; let cool completely.

Step 5

Glaze:Beat confectioners' sugar, lemon juice, and vanilla on medium speed until smooth. Slowly add 1/4 cup milk; beat on medium speed just until combined. Add up to 2 tablespoons more milk, a drop at a time, to reach desired consistency. Drizzle rolls with glaze just before serving.